Selector switch



J. F. HEARN SELECTOR SWITCH Filed Nov. 14, 1925 Patented Oct. 30, 1928.

' UNITED STATES 1,689,340 PATENT. OFFICE.

JOHN I. ERA-RN, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COH-rm, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

snmc'ron swrr cn.

Application filed November 14, 1923. Serial No. 674,637.

The object of this invention is to provide means of constructin andadjusting an improved selector switc of simple and inexpensiveconstruction for use in automatic I telephone systems in variouscapacities, such as a line finder, line switch, or register.

In switches of this general type such as are shown in the patents toDietl No. 1,126,727 (February 2, 1915) and to Adams No. 1,399, 728(December 13, 1921), considerable difliculty has been encountered due,to uneven wearin of the terminals, necessitating the discarding of theentire switch.

A feature of this invention, is the arrangement whereby the rotor may bereadily removed and replaced, without requiring the readjustment of thevarious contacting members of the terminal bank and the rotor.

Another feature of the invention is the substitution of an abrasivewheel for the brush assembly for rinding the terminals to align them ina perfect cylindrical surface.

Another feature of this invention is the construction of the terminalsin a separate unit apart from the stationary element of the switch,whereby its useful life is considerably increased.

Other features will appear from the detailed description.

Fig. 1 is a side view of the switch, Fig. 2 is a section 22 of Fig. 1,and Fig. 3 is a section of the switch similar to Fig. 2 but with thebrush assembly replaced by an abrasive wheel.

The individual terminals 1, are arranged in the form of the arc of acircle and molded in the molding compound 4 in units, each layer formingone unit, and a number of these units, usually six, are encased in thecasing 10 by means of the screws 11. The terminal arc is then ground bymeans of a suitable grinding wheel in order to align the contactingsurfaces of the terminals in the same cylindrical plane. The encasedterminal bank is then secured to the main frame 6 by means of the threescrews 5.

The brushes 9 are secured at 7 by means of rivets to the backstops 22which form a part of the metal carrier 8 which electrically connects theindividual brushes of each pair of brushes together. Each pair ofbrushes 9 is connected to a separate carrier 8, and all the carriers areinsulated from each other and mounted upon the shaft 12 to form a rotaryunit or rotor.

The usual driving unit 13, consisting of an electro-magnet 14, with itsarmature 15, pivoted at 23, carrying the arm 16, to which is secured thepawl 17 for stepping the ratchet 18, is attached to the main frame 6 bymeans of the screw 21. The ratchet 18 which is stepped by the pawl 17forms a part of the rotor, hence each time the pawl 17 makes a completestroke, the ratchet 18, and consequently the rotor, rotates one step ina counter clockwise direction. To prevent the rotor from rotating in aclockwise direction the pawl 19 is provided, which normally engages withone of the teeth of the ratchet 18.

The back stop 20 limits the upward motion of the pawl 17, thuspreventing the rotor from stepping more than one step at a time. Aspring 26 is tensioned between the lug 25, forming a part of themagneticlstructure, and a lug 27 which is an extension of the armature15. When the armature 15 is attracted by the electromagnet 14 the lug 27is moved away from the lug 25, thus tending to increase t e tension ofthe spring 26. The pawl 17 'is also brought into engagement with thenext successive tooth of the ratchet 18, and when the electromagnet 14is deenergized the spring 26 tends to return the armature 15 to normal,thus forcing the pawl 17 to step the rotor one step.

To make the stepping magnet 14 self-interrupting, the arm 16 inoperating causes the insulating cap 28 to force the contact spring 29away from the contact member 30, thus opening stepping magnet circuit.

Each brush 9 is split into two prongs 31 and 32 thus insuring a bettercontact between the brushes and the terminals.

When the rotor is in motion the brushes 9 step from terminal to terminaluntil they pass between the feeder brushes 24 and 33. The feederbrushes, however, are so arranged that the brushes 9 do not makephysical contact with the feeder brushes in passing them.- The feederbrushes, however, do make constant contact with the carrier 8 and asthis pressure is constant, the double load condition, experienced inother switches of this general type, is eliminated.

The bolt 34 (Fig. 6) locks the latch 3 which when in the locked positionbears against the groove 35 in the shaft 12 thus holding the rotor inposition. When the bolt 34 is loosened, the latch 3 which is shaped likean eccentric cam may be turned B loosenin the three screws, 5 thetermi-- nal ank may e removed and re laced without disturbing the othermem ers of the .switch in any way.

Inother switches of this general type, the terminals have of necessitybeen composed of very thin sheet metal, and, since the terminals areworn away by the friction of the brushes, the life of the terminal bankhas been relatively short. In. the present invention, due to the heavyweight of the metal used, and the length of the terminals, which may beworn down until almost flush with the insulating compound, it is evidentthat the useful life of the switch is considerably increased.

Due to the ease with which the rotor and feeder brushes may be removedand the weight of the meta used for the terminals comprising theterminal bank, it is ossible to remove the rotor and feeder brus es,replacing the former by a small grinding element such as is shown in Fi3 of the drawings. This element comprlses a shaft 37 upon which ismounted a circular grinding disc 36, of a width slightly greater thanthe breadth of the terminal assembly. When the shaft 37 is mounted inthe switch frame in place of the brush mounting and the switch rotated,the terminal faces are ground thereby aligning them into the samecylindrical surface. Disc 36 may be of any diameter according to thecurvature of the terminal are desired.

What is claimed is: Y

1. A method of constructing a terminal bank fora rotary switchwhichconsists, in assembling a group of insulated terminals 1n a layer in t egeneral form of the arc of a circle to form a unit, of securing aplurality of the units together to form a bank, of assemblin a grindingunit in the place of the rotata 1e switch member, and of rotatmg thegrinding unit for grinding the ends of the terminals thus assembled toproduce a plurality of contacting terminal ends 1n the same cy indricalsurface.

2. A method of constructin a terminal bank for a rotary switch whicconsists, in securing a group of individual terminals together, mouldingthe terminals together as no unit with a suitable mouldingand'insulating compound of securing a lurality of the units toget er toform a bank, of assembling a grinding unit in the place of the rotatableswitch member, and of rotating the grinding unit for grinding the endsof the terminals thus assembled to produce a plurality of contactingterminal ends in the same cylindrical surface.

3. Method of re-alignin the contactin surfaces of the terminals 0 aterminal ban of a selector switch which consists in replacing therotatable member of the selector switch by a grinding wheel and ofrotating the grinding wheel by a suitable driving means, thus grindingthe contacting surfaces of the terminals to align them all in the samecylindrical lane.

4. Method of re-a igning the contacting surfaces of the terminals of amolded terminal bank of a selector switch, which consists in replacingthe rotatable member of the selector switch by a grindin wheel and ofrotating the grinding wheel ymeans of the selector stepping magnet, thusgrinding the contacting surfaces of the terminals to ge-align them inthe same cylindrical surace.

In witness whereof, I hereunto subscribe my name this 12th day ofNovember A. D.,

JOHN F. HEARN.

